ABC News April 14, 2015

Formerly Conjoined Twins Celebrate First Birthday

WATCH: Conjoined Twins Undergo Complicated Separation Surgery

Formerly conjoined twins Knatalye Hope and Adeline Faith Mata celebrated their first birthday with a "Frozen"-themed party at the hospital.

A team at Texas Children's Hospital separated the girls on Feb. 17 in a 26-hour surgery. They are still in the pediatric intensive care unit and have each had a few surgeries since the separation, but their mother, Elysse Mata, decorated their room with snowflakes and balloons.

"It's been a year," Mata said, surrounded by presents as the hospital filmed her. "It went by so fast. I feel like just yesterday they were born."

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Allen Kramer/Texas Children’s Hospital
Elysse Mata gave birth to conjoined twins at Texas Children’s Hospital in Houston, April 11, 2014.

Earlier in the week, Mata had a party for everyone at the hospital who helped her babies over the last year. She said she was sad to leave some of the doctors from before the separation, but she knows it's a positive thing.

"Now they're good and healthy and hopefully headed towards home," said Mata, 25, of Lubbock, Texas.

Allen S. Kramer/Texas Children's Hospital
The girls celebrated with a Disney's "Frozen" themed birthday party for family and friends at the hospital.

Mata was shocked to learn the twins were conjoined when she was pregnant with them, she told ABC News in July.

"I was speechless, it was so unexpected,” she said.

The girls were born on April 11, 2014 at Texas Children's Hospital. They shared a chest wall, diaphragm, intestines, lungs, lining of the heart and pelvis. Their middle names are Hope and Faith because you can't have one without the other, she said.

"Nightline" was at the hospital in February as 12 surgeons operated on the Mata twins, and Elysse, her husband and 20 family members camped out in the waiting room.

Allen S. Kramer/Texas Children's Hospital
Adeline Mata shown here recovering from a surgery to help with her breathing.
Allen S. Kramer/Texas Children's Hospital
Both girls have undergone new procedures after they were separated in February.
Allen S. Kramer/Texas Children's Hospital
Days after her first birthday , Knatalye underwent surgery to remove the rods in her pelvis and also to add a gastrostomy button for her feedings.